microsoft / microsoft/TypeScript
@ts-expect-error not ignoring next line correctly in JSX, and errors are reported on the same line
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Description
🔎 Search Terms
"tsx expect error", "jsx expect error"
🕗 Version & Regression Information
It seems as though @ts-expect-error reports errors on the wrong line, when used inside JSX. For example:
function TestNotIgnoring() {
return <Component>
<div />
{/* @ts-expect-error */} <-- error
{child}
</Component>
}
function TestIgnoring() {
return <Component>
{/* @ts-expect-error */}
{child}
</Component>
}
The error in this case is:
Type 'ReactNode | Element' is not assignable to type 'ReactNode'.
Type 'Element' is not assignable to type 'ReactNode'.
Type 'Element' is missing the following properties from type 'ReactPortal': type, props, key(2322)
Unused '@ts-expect-error' directive.(2578)
I would have expected no error though, given that that's the behavior when other children are added. Other examples that work are:
function TestIgnoringOnLineAbove() {
return <Component>
{/* @ts-expect-error */} <-- moved expect *above* the div, works correctly
<div />
{child}
</Component>
}
I'd expect this to not work though, given that the error is actually on the line with {child} in it
⏯ Playground Link
💻 Code
import React from 'react';
function Component({
children
}: {
children: React.ReactNode
}) {
return <div>{children}</div>
}
const child = 'Example' as (React.ReactNode | Element)
function TestNotIgnoring() {
return <Component>
{/* @ts-expect-error */}
<div />
{child}
</Component>
}
function TestIgnoring() {
return <Component>
{/* @ts-expect-error */}
{child}
</Component>
}
function TestIgnoringOnLineAbove() {
return <Component>
{/* @ts-expect-error */}
<div />
{child}
</Component>
}
🙁 Actual behavior
@ts-expect-error was reported unused, and an error was reported on the line including ts-expect error
🙂 Expected behavior
@ts-expect-error should suppress the error, regardless of whatever other elements are added as children prior to the element.
Additional information about the issue
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked TypeScript Playground reproduction and compare the two JSX cases where @ts-expect-error is placed before a child expression. Trace how JSX child diagnostics and directive locations are associated, then verify that the directive suppresses the intended error without producing an unused-directive diagnostic.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- react, typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100